CN1286744A - Slave-cylinder housing made of plastics and contg. guide sleeve made of steel - Google Patents

Abstract

A hydraulic clutch release system (1) for a vehicle friction clutch comprises a cylinder (2) and a guide sleeve (6). The guide sleeve (6) is radially spaced apart from the wall (5) of the cylinder (2) and from a gearbox input shaft (3). A cylinder (2) made of plastics is combined with a guide sleeve (6) made of steel and formed without cutting. The guide sleeve (6) is secured in the cylinder (2) by a snap lock (23).

Description

Plastic receiving cylinder housing in which metal guide bushings are housed

Technical Field of the Invention

The invention relates to a hydraulically actuated release device, which can also be referred to as a center release, for a friction clutch of a motor vehicle. It consists of a receiving cylinder (Nehmerzylinder) mounted concentrically to the transmission drive shaft and a piston. Here, the receiving cylinder is implemented as a piston-cylinder-unit and has a cylinder detachably fastened to the gearbox housing; while the piston is guided on a guide sleeve which is connected to the cylinder The wall and the drive shaft of the gearbox are all spaced at a certain distance in the radial direction. In this case, the guide sleeve has an annular connecting flange at its one end, which is arranged at a mounting point between the gearbox housing and the end face of the cylinder. The piston, which delimits the pressure chamber, is equipped with a seal which rests in a sealing manner against the cylinder wall and the guide sleeve. In this case, the piston is equipped with a release bearing on its side facing away from the pressure chamber, which bears against the release lever of the friction clutch in the assembled position. A pressure medium can be applied to the pressure chamber. The medium can be fed through a radial pressure pipe integrated with the cylinder. The latter has, in addition to a pressure medium supply, also a venting device for the separating device.

Background Art of the Invention

A kind of such separating device is known among DE 4313346. In this prior art, its receiving cylinder comprises two radially spaced tubular thin steel plate members, which are sealedly connected to each other on the side facing the gearbox housing and cannot be separated. The radially outer sheet-metal component is provided with an opening for supplying the pressure chamber with pressure medium. A tube fits into the hole and is secured by welding. A receiving cylinder of this type made entirely of steel components is cumbersome to assemble and has a great weight. Since the pressure pipe, as an independent component, needs to be placed in the tubular thin steel plate component on the radially outer side, thus in addition to increasing the number of components, another separation location is produced.

A kind of separating device is disclosed among DE-A 4129370, and its piston-cylinder-unit comprises a single-piece cylinder made of plastics. Such a plastic cylinder needs to be manufactured through a cumbersome injection molding process, thereby increasing the manufacturing cost. Due to the undercuts included in the block profile, only thermoplastics can be used as it allows forced demolding. In order to meet the strength requirements, the thickness of the cylinder wall made of plastic is very large, which leads to an increase in the component size. Relatively elastic thermoplastics have high thermal expansion and thus require additional measures for sealing the piston.

Tasks of the invention

The object of the present invention is to improve the prior art in order to realize a receiving cylinder with optimized structural dimensions that can be produced economically.

Technical scheme of the present invention

In the present invention, the above-mentioned task is achieved by the features of claim 1 .

From the perspective of accepting that the cylinder body can meet the strength requirements and have suitable manufacturing costs, the solution that can achieve the best combination of the two is: use plastic to manufacture the cylinder body by injection molding process, injection pressure or die-casting method, and use metal The guide sleeve is produced without cutting by means of a deep-drawing process, and the two are reconnected. Due to the shape of the cylinder, which according to the invention only surrounds the outer wall of the annular pressure chamber, the injection molding process is particularly suitable for the production of components of this type. In this case, the wall dimensions of the pressure chamber can be selected according to the required permanent strength without affecting or exceeding the radial space predetermined by the outer dimensions of the release bearing. According to the invention, such a plastic housing can be combined with a thin-walled, non-cutting-produced steel guide sleeve produced by deep-drawing. The cooperation of components made of different materials in the present invention can ensure that: as the receiving cylinder, the heat generated during operation and the resulting thermal expansion will not affect the function of the receiving cylinder, especially the sealing performance.

Such a receiving cylinder structure can be produced economically, since reworking of the sliding surfaces of the seal is omitted, the required component space is optimized, and the durability is improved. At the same time, due to the use of the guide sleeve made of metal, especially steel plate, the critical guiding performance of the piston is improved, especially compared with the one-piece active cylinder housing made of plastic. In order to achieve the preassembled component unit, the end-face annular connecting flange of the guide sleeve is fastened to the cylinder body by a non-positive connection, in particular by a snap-in connection.

In the structure of the present invention, the plastic cylinder is manufactured using a die-casting method. In the sealing area, ie in the area of the sliding surfaces of the sealing lips on the cylinder wall and on the guide sleeve, no rework or treatment is required.

The concept of the invention also includes that the cylinder body has a taper in the region of its cylinder wall, ie in the region of the guide track of the radially outer sealing lip of the sealing piston. The forming gradient here is constructed in such a way that the maximum diameter of the cylinder wall is designed on the side facing the release bearing, and the inner clear width of the guide track shrinks continuously over the entire length of the cylinder wall towards the gearbox side, where the forming A valid value for the slope is at least 0.5°. Because, as the friction clutch disc wears, the neutral position of the piston is displaced in the direction of the gearbox housing, and the seals of the piston are also worn. Thus, the construction of the cylinder wall in the present invention provides wear compensation for the piston seals. The reduction in the diameter of the cylinder wall should compensate for the wear of the sealing lip of the piston seal. In this way, during the entire service life of the friction clutch, the pressing force of the outer sealing lip remains basically constant, avoiding the risk of leakage.

The plastics used to make the cylinder are preferably thermosetting plastics, such as phenolic plastics, amino plastics, EP-resins, and UP-resins. After adding appropriate fillers and reinforcing agents, this plastic has a strength value approximately equal to that of aluminum. In addition, compared with other plastics, thermosetting plastics are characterized by low thermal expansion and high breaking strength. Also, the option of using thermoplastics such as polyamide and PPA is included in the invention.

In order to realize the simple and efficient clamping connection between the annular connecting flange on the guide sleeve and the cylinder body, a step is made on the circumference of the annular connecting flange. In this case, an axial section is formed on the annular connecting flange, which has a radially outwardly facing edge at its free end, which snaps into an undercut of the annular groove in the assembled position. As an assembly aid, the ring groove is provided on the outside with an introduction bevel, which facilitates insertion of the ring flange edge. The clamping connection in the present invention is entirely for providing transportation safety assurance, which enables the pre-assembled active cylinder body to remain as a whole. In the assembled state of the receiving cylinder, the annular connecting flange of the guide sleeve is fastened between the gearbox housing and the end face of the cylinder.

According to another feature of the invention, the pressure pipe of the housing is provided with spaced apart longitudinal holes or longitudinal passages for conveying pressure medium, supplying air and exhausting the separating device. At the free end of the pressure pipe, a pressure connection pipe is provided for one longitudinal hole, and a valve is provided for the other hole in order to complete the air supply and exhaust to the separation device. The outlets on these pressure pipes are effectively sealed, for example by welding, gluing, pressing or screwing on by means of separate components.

When the plastic cylinder body of the present invention is reliably fixed on the gearbox housing through bolt connection, as an improvement measure, a steel sleeve is placed in the receiving hole of the fastening ear on the cylinder body. This way, the plastic does not have uncontrollable rheology when the bolt is tightened. A radially biased and slotted steel sleeve is preferably used, the length of which is less than the wall thickness of the fastening sleeve, so that a controlled clamping of the plastic by the fastening screw is achieved. It is also advantageous to assign a washer to the steel sleeve on the side of the screw head, by means of which the area of the compressed plastic in the region of the fastening lug can be increased.

Brief description of the drawings

The present invention is illustrated by an embodiment and 4 figures in total. in:

The structure of a pre-assembled active cylinder of Fig. 1;

A longitudinal sectional view of the cylinder block and the guide sleeve of the active cylinder shown in Fig. 2 Fig. 1;

The front view of the active cylinder shown in Fig. 3 Fig. 1;

Figure 4. Partial enlarged view of "Z" in Figure 2.

Detailed description of the drawings

In Fig. 1 there is shown a hydraulically operable separating device 1 of known type, also called a central separator. The design of the separating device 1 comprises a piston-cylinder unit, the cylinder 2 of which is arranged concentrically around a transmission drive shaft 3 and is fastened detachably to the transmission housing 4 by a screw connection. A guide sleeve 6 is arranged in the cylinder body 2, and there is a certain distance between it and the cylinder wall 5 and the drive shaft 3 of the gearbox along the radial direction. It is made of metal materials, especially thin steel plates, without cutting by deep drawing. On the side facing the gearbox housing 4, an annular connecting flange 7 is formed on the guide sleeve 6, which has several steps and is clamped at the position between the cylinder block 2 and the gearbox housing 4 . Between the guide sleeve 6 and the cylinder wall 5 is formed a circular annular space which forms the pressure chamber 8 . The pressure chamber 8 is delimited axially by an annular connecting flange 7 and a piston 9 . On the side of the pressure chamber, a grooved sealing ring 10 is assigned to the piston 9 , the sealing lip of which rests tightly on the guide sleeve 6 and the cylinder wall 5 in a sealing manner. At the end facing away from the pressure chamber 8 a release bearing 11 is fixedly mounted on the piston 9 . After the disengagement device 1 is installed, it is supported on the disengagement lever of the friction clutch. In order to activate the friction clutch not shown in FIG. 1 , it is necessary for the piston 9 to move axially from the above position to the lower position. The movement of the piston can be effected by applying a pressure medium into the pressure chamber 8 . For this purpose, a radial pressure line 12 integrally formed with the cylinder body 2 is provided. It is bent at a right angle at its free end and has a pressure connection 13 ( FIG. 3 ) for connection to a pressure pipe. This pipe connects the separating device 1 to a master cylinder which can be manually operated by means of an attached pivoting device not shown in FIG. 1 . Here, the pressure tube 12 has two longitudinal bores 14 , 15 shown in FIG. 3 which are axially spaced apart. The longitudinal bore 14 serves to supply and exhaust the pressure chamber 8, for which purpose a valve 16 is provided at its free end oriented vertically. The function of the other longitudinal hole 15 is solely for conveying pressure medium. In order to obtain an effective sealing effect, the outlets of the two longitudinal holes 14, 15 are all closed with plugs 17, 18, and preferably fixed by welding or bonding.

FIG. 2 shows a cylinder 2 which forms a housing unit with a guide sleeve 6 . The figure shows the advantages afforded by the invention. The cylinder block 2 produced by injection molding of plastic requires no subsequent machining of the sliding surfaces of the sealing lips in the section of the cylinder wall 5 and the guide sleeve 6 . This creates an advantage in terms of costs. The structure in which the cylinder body 2 and the pressure pipe 12 are integrally connected avoids a separated position, thus making it have higher rigidity. The relatively thin-walled guide sleeve 6 made of metal can be produced in large quantities by deep-drawing methods without cutting, reducing costs. Compared to a one-piece receiving cylinder housing made of plastic, the steel guide sleeve, in addition to reducing the radial dimensions, also provides a more effective guidance for the piston 9 . Therefore, the heat generated by all components in the separating device 1 during operation has no influence on the guidance of the piston. Furthermore, the cylinder block 2 has a cylinder wall 5 on which the radially outer sealing lip of the grooved sealing ring 10 ( FIG. 1 ) is guided. The cylinder wall has a profiled bevel or taper with a larger diameter "D" on the side of the release bearing and a continuous decrease in diameter to "d" over the length "1".

This taper compensates for piston seal wear. The reason is that the neutral position of the piston 9 moves toward the gearbox housing 4 as the wear of the friction clutch-transmission plate increases. The diameter reduction here matches as much as possible the reduction of the sealing lip extrusion force of the groove seal ring 10 due to wear.

The fastening lugs 19 of the cylinder 2 can be seen from the front view shown in FIG. 3 . They are distributed along the circumference. The holes 20 therein are used to receive fixing bolts. For reasons of strength, a slotted, radially biased steel sleeve 21 is inserted into the bore 20 . They limit the compressive forces to which the plastic in the vicinity of the fastening lugs 19 is subjected when the fastening screws are tightened. In addition, a washer 22 may be arranged on the side of the steel sleeve 21 close to the bolt head to support the bolt head. FIG. 3 also shows the configuration of the pressure tube 12 in which there are two axially spaced longitudinal bores 14 , 15 . Connected to them are a vertically oriented pressure connection 13 at the free end of the pressure line 12 and a valve 16 .

In FIG. 4 , the “Z” area in FIG. 2 is partially enlarged, showing the snap-fit connection 13 between the annular connecting flange 7 and the cylinder body 2 . The snap-in connection 23 forms a safety feature by which the guide sleeve 6 is held on the cylinder body 2 . In the form of the snap-fit connection 23 , the annular connecting flange 7 of the guide sleeve 6 has a right-angled flange on the circumference to form an axial section 24 . It has a radially outwardly facing edge 25 at its end. Furthermore, the cylinder body 2 has an annular groove 26 on the end face. In order to facilitate the insertion of the axial section 24 during assembly, it is provided with an introduction bevel 27 on its outside as an aid. The ring groove 26 also has an undercut 28 into which the edge 25 engages in the assembled state of the guide sleeve 6 . The cylinder body 2 is processed with a slit 29 concentric with the ring groove 26, and its length exceeds the ring groove 26. When the axial section 24 of the guide sleeve 6 is introduced, it enables the snap-in nose 30 to be easily deflected in the radial direction. In order to make the guide sleeve 6 fixed on the cylinder body 2 and cannot rotate, the present invention also includes an embodiment in which a segment that is not the entire circumference is used to replace the entire circumference of the axial segment 24 . They cooperate with grooves distributed along the circumference on the cylinder body 2 .

 Reference Signs Table 1. Separation device 16. Valve 2. Cylinder body 17. Plug 3. Transmission drive shaft 18. Plug 4. Gearbox housing 19. Fixed ear 5. Cylinder wall 20. Hole 6. Guide sleeve 21. Steel casing 7. Ring connection flange 22. Gasket 8. Pressure chamber 23. Card connection 9. Piston 24． Axial section 10. Groove seal ring 25. edge11. Release bearing 26. Annular groove 12. Pressure pipe 27. Lead-in slope 13. Pressure connection pipe 28. Concave 14. Longitudinal hole 29. Grooving 15． Longitudinal hole 30. Snap nose

Claims (10)

1. Hydraulically operable release device (1) for friction clutches in motor vehicles, comprising a receiving cylinder mounted concentrically to the drive shaft (3) of the gearbox, which is made as a piston-cylinder-unit and has a fixed The cylinder block (2) on the gearbox housing (4); also includes a piston (9), which is placed on a guide sleeve radially spaced at a certain distance from the cylinder wall (5) and the gearbox drive shaft (3). is guided on the pipe (6), here, the guide sleeve (6) has an annular connecting flange (7) at one end, which is arranged between the gearbox housing (4) and an end face of the cylinder (2) In the installation position between them, the annular connecting flange (7) and the piston (9) jointly form the boundary of an annular pressure chamber (8), which can be applied with a pressure medium, which can pass through a Conveyed by a radial pressure line (12) integrally connected to the cylinder (2), which, in addition to a pressure medium supply line, also has a ventilation line for the separating device (1), wherein a piston is assigned a Groove seal (10), which bears sealingly against the cylinder wall (5) and the guide sleeve (6), while a release bearing is arranged on the side of the piston (9) facing away from the pressure chamber (8) (11), which is characterized in that: a metal guide sleeve (6) is installed in the cylinder body (2) made of plastic, and its annular connecting flange (7) is connected by a clamping connection (23) Be fixed on the cylinder body (2). 2. Separating device according to claim 1, characterized in that the sealing lip of the grooved sealing ring (10) rests in a sealing manner on the unprocessed injection-molded surface of the cylinder wall (5). 3. The separation device according to claim 1, characterized in that: the cylinder wall (5) has a taper of at least 0.5°, wherein the diameter "D" starts from the release bearing (11) side and passes through a length "1" continuously Shrink to "d". 4. The clutch system according to claim 1, characterized in that: the plastic used to manufacture the cylinder (2) is preferably a thermosetting plastic, such as phenolic plastic, amine-based plastic, EP-resin or UP-resin. 5. The separation device according to claim 1, characterized in that: the circumference of the annular connecting flange (7) is made into a stepped shape, forming an axial section ( 24), the radial edge (25) of the axial section snaps into an undercut (28) of the cylinder (2). 6. Separating device according to claim 5, characterized in that the axial section (24) forms an introduction bevel (27) on the outside. 7. The separation device according to claim 1, characterized in that: at the free end of the pressure pipe (12), the longitudinal holes (14, 15) for the pressure medium delivery and the air supply and exhaust of the separation device (1) are Seal closed. 8. Separating device according to claim 1, characterized in that the valve (16) for venting the separating device (1) and the pressure connection line (13) are non-detachably connected to the pressure line (12). 9. The separation device according to claim 1, characterized in that: in the fixed ear (19) of the cylinder (2), there is a steel sleeve (21) for receiving the bolt and passing it through the cylinder ( 2) The bolts are fixedly connected to the gearbox case (4). 10. Separating device according to claim 9, characterized in that radially biased, slotted steel sleeves (21) are used which are provided with washers on the side of their bolt heads.

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